Fluid storage tanks



Jan. 9, 1968 w. KOHRING 3,362,559

FLUID STORAGE TANKS Filed Nov. 6, 1964 2 Sheets-Sheet 1 Fig.1.

: I INVENTOK 2 )Valtiua) BY \aimbcow loczs ATTORNEY Jan. 9, 1968 w.KOHRING FLUID STORAGE TANKS 2 Sheets-Sheet 2 Filed Nov. 6, 1964 IVENTOl-Z BY 59-h ATTORNEY United States Patent ice 3,362,559

3,362,559 FLUID STORAGE TANKS Walter Kohring, Garwood Cottage, ChurchRoad, Rawreth, near Wickford, Essex, England Filed Nov. 6, 1964, Ser.No. 409,547 12 Claims. (Cl. 220-9) This invention relates to a fluidstorage tank and is particularly although not exclusively applicable toa tank for the cryogenic storage of liquefied gases. The invention alsorelates to a method of heat insulating such a tank.

Such tanks are often of very large size and are double walled having aninner storage vessel located within an outer casing the space betweenthe vessel and the casing containing heat insulating material. The tanksare frequently of cylindrical shape either square or circular in crosssection about a vertical axis and are supported on a flat base.

The heat insulating material usually preferred comprises loose particleswhich may be of irregular shape and size such as for example amica-based substance; it may be in the form of a powder or it may be inthe form of hollow substantially spherical particles. In all these caseshowever the particles in known manner provide a multiplicity of pocketsso that gas trapped therein acts as the effective heat insulatingmedium.

With the bulk storage of liquid gases at cryogenic temperatures theinner storage vessel is from time to time subjected to very largetemperature changes (of the order of 300 C.) and with a vessel of largesize (for example in excess of 100 ft. diameter) radial movement of itswalls can be of the order of 4 to 6 inches. Since the outer casingremains stationary during any such expansion and contraction of theinner vessel the heat insulating material is subject to considerablecompression on expansion of the storage vessel and although someexpansion of the material may occur on contraction of the vessel troubleis experienced in the formation of voids generally alongside the wall ofthe vessel.

Although most insulating materials of the type described above tend toflow freely in the uncompressed state compression causes them to cake.Upon contraction of the inner vessel support is removed from the innersurface of the caked material and the weight of the latter causes linesof cleavage to occur apparently haphazardly therethrough so that thematerial tends to settle towards the base of the tank some of itreverting to a flowable state but some of it remaining in a cakedcondition. Thus a multiplicity of voids some of considerable size areleft between the inner vessel and the outer casing and the overall levelof the material will need to be topped-up. Thus the heat insulation ofthe inner vessel will be seriously impaired.

In addition and depending upon the nature of the insulating materialexpansion of the inner vessel could cause large and undesirablepressures to be transmitted to the outer casing which is not intended towithstand excessive localised internal pressure.

It is an object of the present invention to provide an improvedconstruction of fluid storage tank and a method of heat insulating sucha tank. Particularly although not exclusively it is an object to providean improved storage tank for the cryogenic storage of liquefied gaseswhich permits particulate heat insulating material to be used betweenthe inner vessel and the outer casing while reducing the disadvantagesset forth above,

According to one aspect of the invention a method of heat insulating afluid storage tank includes locating around at least part of the tank inspaced relationship thereto a framework which in vertical sectioncomprises a number of vertically spaced apart members and dis- PatentedJan. 9, 1968 posing particulate heat insulating material between theframework and the vessel so that the material is constrained by themember.

According to another aspect of the invention a method of heat insulatinga fluid storage tank comprises constraining a quantity of particulateheat insulation material around the tank by a framework which invertical section comprises a number of vertically spaced apart membersarranged so that the material adopts its natural angle of repose betweeneach member and the next lower member.

Another aspect of the invention provides a fluid storage tank comprisingan inner storage vessel and a framework located outwardly of and spacedfrom the vessel the framework comprising in vertical section a number ofvertically spaced apart members arranged so that particulate heatinsulating material disposed between the vessel and the framework isconstrained by the latter.

Yet another aspect of the invention provides a fluid storage tankcomprising an inner storage vessel and framework located outwardly ofand spaced from the vessel the framework comprising in vertical sectiona number of vertically spaced apart members arranged so that particulateheat insulating material disposed between the vessel and the frameworkfalls freely at its natural angle of repose between each member and thenext lower member.

Several embodiments of the invention will now be described by way ofexample with reference to the accompanying drawings in which:

FIG. lshows in axial section the lower part of a cryogenic storage tankaccording to the invention,

FIG. 2 is an elevational view of part of a framework,

FIG. 3 shows diagrammatically an elevational view partly in section of amodified construction,

FIG. 4 is a section on the line IVIV of FIG. 3,

FIG. 5 is a fragmentary perspective view of part of the construction ofFIG. 3,

FIG. 6 is a diagrammatic view in vertical section of another arrangementand FIG. 7 is a diagrammatic plan view of another arrangement.

Referring to FIG. 1 of the drawings this shows a modification of aconstruction fully described in the specification of co-pendingapplication Ser. No. 253,584, now abandoned comprising an inner storagevessel 1 mounted upon a concrete base 2 and located by long bolts 3extending through sockets 4 into the ground 5 beneath the base 2. Anouter casing 6 is provided in spaced relationship to the vessel 1 and inthe previous arrangement it is assumed that the annular spacetherebetween is filled with particulate heat insulating material.

In the arrangement of the present invention a framework indicatedgenerally at 7 is disposed between the wall of the vessel 1 and the wallof the outer casing 6 and in vertical section as shown comprises anumber of vertically spaced inwardly and downwardly inclined lamellae 8secured to a supporting structure which includes a number of struts 9joining the outermost parts of the lamellae and as shown in FIG. 2extending at an acute angle to the vertical. It will be understood thatadditional supporting struts than those shown may be employed ifrequired and that the framework is supported by the base 2.

The lamellae 8 comprise discrete annuli of circular or polygonal shapein plan.

As shown in FIG. 1 particulate heat insulation material 10 is disposedbetween the vessel 1 and the framework 7 the lamellae 8 being sovertically spaced apart and extending radially of the vessel 1 by such adistance that the material It) falls naturally as shown at 11 at itsnatural angle of repose between one lamellae and the next lowermostlamella.

It will be understood that when the vessel 1 expands the lamellae 8tends to introduce lines of cleavage into the bulk of the material 10causing the latter to ride up the upper surfaces of the lamellae anddepending upon the extent of expansion of the material some of it mayspill and fall into the space 12 between the framework 7 and the outercasing 6. In this respect the struts 9 constitute spillage conductorstending to guide the overflow into specific circumferential locationsaround the framework. It will be appreciated that with this arrangementthe space 12 can constitute a walkway with suitable access (not shown)provided in the casing 6 to permit periodic inspection and ready removalof the spillage.

Although in the preferred form the upper surfaces of the lamellae 8 areinclined downwardly and inwardly towards the vessel 1 so that at leastto some extent when contraction of the vessel occurs after expansionthereof some of the material 10 will slide back down the lamellae tooccupy the position shown in FIG. 1 these lamellae could be constitutedby members of different shape and indeed their upper surfaces could beat different inclinations from that shown. The upper surfaces could forexample be horizontal or it would be possible to have a small reverseslope so long as this was less than the angle of repose of the materialand the radial dimension of the surface was suflicient to accommodatethe necessary free fall 11 between successive lamellae. In addition theupper surfaces of the members could be curved.

FIG. 3 is of the drawings shows a modified arrangement in which a singlehelical strip 8a is disposed around the inner storage vessel 1 invertically spaced apart turns to provide the lamellae 8. The turns areheld in place by a number of circumferentially spaced verticallyextending supports 9a which are secured at their lower ends to the base2 by bolts (not shown) and are disposed inwardly of the strip 8a. Thesupports are generally cusp shaped in horizontal section having two armsand 90 formed with inclined slots such as 9d to receive the lamellae 8.The arrangement of the supports 9a is shown more clearly in FIGS. 4 and5.

It will be understood that with this arrangement the strip 8a could, fortransport purposes prior to assembly, be wound into a coil of suchsmaller diameter than required in the assembled installation.

FIG. 6 shows diagrammatically an arrangement which can be used with theconstructions of FIG. 1 and FIG. 3 whereby the upper part of theframework '7 terminates short of the upper part of the outer casing 6and the latter is formed at its upper extremity with an open hopper 13having an inclination greater than the natural angle of repose of thematerial 10 the latter extending from the upper part of the frameworkinto this hopper and the space 12 being connected at a number oflocations over fluidised pipelines 14 so that spillage can be returnedto the hopper 13. In a further modification not shown in the drawing,the space 12 is connected via suitable channels to a storage chamberlocated centrally below the tank so that a single fluidised connectiontherefrom may be used to return the spillage of the material 10 to thehopper 13.

FIG. 7 of the drawings shows diagrammatically in plan with the upperpart cut away another arrangement in which a symmetrical arrangement ofcylindrical tanks 1 each surrounded by a framework 7 (which may be inaccordance with FIGS. 1 and 2 or FIGS. 3 to is disposed within a singleouter casing 6.

It will be understood that with this arrangement as indeed with thearrangements of FIGS. 1 and 3, it is possible to have the outer casing 6of lightweight construction to constitute merely a weatherproofenclosure since it is not subjected to any stresses as a result ofexpansion and contraction of the storage vessel or vessels themselves.For example, it would be possible for the outer casing 6 to be oflightweight plastic sheet material.

Although in the examples described above it is assumed that the storagetanks are very large it will be understood that it is possible toutilise the heat insulation arrangement of the present invention forsmaller structures and for example several tanks together with theirassociated framework 7 could be accommodated in an existing building.

It will further be understood that although the tanks described aboveare of cylindrical form having a circular cross-sectional shape, theycould be cylindrical but of other cross-sectional shape or they could bespherical or part-spherical.

I claim:

1. A fluid storage tank comprising a storage wheel, a framework locatedoutwardly of and spaced from the vessel, said framework comprising invertical section a number of vertically spaced annular radially inwardlyand downwardly sloping members, particulate heat insulating materialdisposed between the vessel and the framework, the exterior face of saidmaterial extending at the natural angle of repose thereof respectivelybetween each member, an outer casing surrounding and spaced from theframework, a hopper at the upper extremity of the outer casing at leastone wall of the hopper having an inclination greater than the naturalangle of repose of the material the said material extending from theupper part of the framework into the hopper and means for moving any ofsaid material spilled into the lower part of the space between theframework and the outer casing to the hopper.

2. A fluid storage tank according to claim 1 in which said meanscomprises pipelines connected between a number of locations in saidspace and the hopper.

3. A fluid storage tank according to claim 1 comprising a chamberbeneath the vessel, channels connecting said space to the chamber and apipeline connected between the chamber and the hopper.

4. A fluid storage tank installation comprising a plurality of tanksaccording to claim 1 disposed within a single outer casing.

5. A fluid storage tank comprising a storage vessel, an outer casingspaced from the vessel, a framework located between the vessel and theouter casing and spaced both from the vessel and the outer casing saidframework comprising, in vertical section, a number of vertically spacedapart substantially horizontally extending members, particulate heatinsulating material disposed between the ves sel and the framework, theouter face of said material extending at the natural angle of reposethereof respectively between each member and the next lower member, thematerial being constrained against the vessel and out of contact withthe outer casing,

6. A fluid storage tank according to claim 5 in which the memberscomprise discrete annular lamellae extending in generally horizontalplanes.

7. A fluid storage tank according to claim 5 in which the memberscomprise individual turns of a single helical strip.

8. A fluid storage tank installation comprising a plurality of tanksaccording to claim 5 disposed within a single outer casing.

9. A fluid storage tank comprising a storage vessel, an outer casingspaced from the vessel a framework located between the vessel and theouter casing and spaced both from the vessel and the outer casing saidframework comprising, in vertical section, a number of vertically spacedapart members, upper surfaces of said members which are inclineddownwardly towards the vessel, particulate heat insulating materialdisposed between the vessel and the framework separate faces of saidmaterial extending at the natural angle of repose thereof respectivelybetween each member and the upper surface of the next lower member thematerial being constrained against the vessel and out of contact withthe outer casing.

10. A fluid storage tank comprising a storage vessel, an outer casingspaced from the vessel, a framework located between the vessel and theouter casing and spaced both from the vessel and the outer casing, saidframework comprising in vertical section a number of generallyhorizontally extending vertically spaced apart discrete annular lamellaeinclined downwardly towards the vessel, particulate heat insulatingmaterial disposed between the vessel and the framework, the outer faceof said material extending at the natural angle of repose thereofrespectively between each lamella and the next lower lamella thematerial being constrained against the vessel and out of contact withthe outer casing.

11. A fluid storage tank comprising a storage vessel, an outer casingspaced from the vessel, a framework located between the vessel and theouter casing and spaced both from the vessel and the outer casing saidframework comprising in vertical section a number of vertically spacedapart turns of a single helical strip an upper surface of said turnsinclined downwardly towards the vessel, particulate heat insulatingmaterial disposed between the vessel and the framework, the outer faceof said material extending at the natural angle of repose thereofbetween each turn and the upper surface of the next lower turn, thematerial being contrained against the vessel and out of contact with theouter casing.

12. A fluid storage tank according to claim 11 comprisingcircumferentially spaced vertically extending supports disposed inwardlyof the strip the supports being V-shaped in horizontal section havingtwo arms formed with inclined slots to receive the turns.

References Cited THERON E. CONDON, Primary Examiner.

I. R. GARRETT, Assistant Examiner.

1. A FLUID STORAGE TANK COMPRISING A STORAGE WHEEL, A FRAMEWORK LOCATEDOUTWARDLY OF THE SPACED FROM THE VESSEL, SAID FRAMEWORK COMPRISING INVERTICAL SECTION A NUMBER OF VERTICALLY SPACED ANNULAR RADIALLY INWARDLYAND DOWNWARDLY SLOPING MEMBERS, PARTICULATE HEAT INSULATING MATERIALDISPOSED BETWEEN THE VESSEL AND THE FRAMEWORK, THE EXTERIOR FFACE OFSAID MATERIAL EXTENDING AT THE NATURAL ANGLE OF REPOSE THEREOFRESPECTIVELY BETWEEN EACH MEMBER, AN OUTER CASING SURROUNDING AND SPACEDFROM THE FRAMEWORK, A HOPPER AT THE UPPER EXTREMITY OF THE OUTER CASINGAT LEAST ONE WALL OF THE HOPPER HAVING AN INCLINATION GREATER THAN THENATURAL ANGLE OF REPOSE OF THE MATERIAL THE SAID MATERIAL EXTENDING FROMTHE UPPER PART OF THE FRAMEWORK INTO THE HOPPER AND MEANS FOR MOVING ANYOF SAID MATERIAL SPILLED INTO THE LOWER PART OF THE SPACE BETWEEN THEFRAMEWORK AND THE OUTER CASING TO THE HOPPER.